Revert "libvmclient: Take VmCallback in VmInstance::start()"

Revert submission 3408863

Reason for revert: Likely culprit for b/391356639  - verifying through ABTD before revert submission. This is part of the standard investigation process, and does not mean your CL will be reverted.

Reverted changes: /q/submissionid:3408863

Change-Id: Id9436b9557e0fd4cbc94df9f22ba35132619aa91
diff --git a/guest/rialto/tests/test.rs b/guest/rialto/tests/test.rs
index 48e3ccb..c94a0e3 100644
--- a/guest/rialto/tests/test.rs
+++ b/guest/rialto/tests/test.rs
@@ -342,6 +342,7 @@
         /* consoleIn */ None,
         log,
         /* dump_dt */ None,
+        None,
     )
     .context("Failed to create VM")
 }
diff --git a/guest/trusty/security_vm/launcher/src/main.rs b/guest/trusty/security_vm/launcher/src/main.rs
index 2fedc16..8dd7c43 100644
--- a/guest/trusty/security_vm/launcher/src/main.rs
+++ b/guest/trusty/security_vm/launcher/src/main.rs
@@ -101,9 +101,10 @@
         None, // console_out
         None, // log
         None, // dump_dt
+        None, // callback
     )
     .context("Failed to create VM")?;
-    vm.start(None /* callback */).context("Failed to start VM")?;
+    vm.start().context("Failed to start VM")?;
 
     println!("started trusty_security_vm_launcher VM");
     let death_reason = vm.wait_for_death();